• MOOC coordinators Manuel Gértrudix Barrio & Rubén Arcos Martín
  • Content written by Ileana Surdu
  • Multimedia design by Alejandro Carbonell Alcocer
  • Visual Identity by Juan Romero Luis

Identifying and avoiding logical fallacies

Evidence, judgement, and logical reasoning

Logical fallacies are errors in logical reasoning. They can either be formal – when arguments are presented in an incorrect form, and just become nonsense, or informal – when the content of the arguments is incorrect (Ferrer, D. 2019). A discourse may encounter a series of informal fallacies, which communicators must be able to both identify (in communications) and avoid (in their communications):

  1. Ad hominem fallacy (lat: against the man) - using personal attack-language on the basis of personal aspects (e.g. gender, physical aspect, ethnicity etc.);
  2. Strawman argument - attacking an imaginary position;
  3. Appeal to ignorance (argumentum ad ignorantiam) – supporting exclusive claims with the same argument;
  4. False dilemma/ false dichotomy – considering only two options out of many possibilities;
  5. Slippery slope – using unlikely extreme future outcomes as argument for a present activity;
  6. Circular argument (petitio principii) – repeating an already assumed argument;
  7. Hasty generalization – general statement in lack of sufficient evidence;
  8. Red herring fallacy – distracting from the argument with an apparent relevant emotion;
  9. Tu quoque/ you too fallacy – turning the attention on others;
  10. Causal fallacy – using logical breakdowns for identifying a cause;
  11. Fallacy of sunk costs – continuing an activity because of the past efforts put into it, without analyzing future costs;
  12. Appeal to authority (argumentum ad verecundiam) – misusing authority;
  13. Equivocation (ambiguity) – using deliberately confusing elements;
  14. Appeal to pity (argumentum ad misericordiam) – appealing to compassion, even if not relevant to the argument;
  15. Bandwagon fallacy – accepting an argument because others agree with it. (Ferrer, D. 2019)


Methodology and Resources